plutonic rock

A pluton in geology is an intrusive igneous rock body that crystallized from a magma below the surface of the Earth. Plutons include batholiths, dikes, sills, laccoliths, lopoliths, and other igneous bodies. In practice, "pluton" usually refers to a distinctive mass of igneous rock, typically kilometers in dimension, without a tabular shape like those of dikes and sills. Batholiths commonly are aggregations of plutons. The most common rock types in plutons are granite, granodiorite, tonalite, and quartz diorite.
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Noun
1. large mass of intrusive igneous rock believed to have solidified deep within the earth
(synonym) batholith, batholite, pluton
(hypernym) igneous rock
(hyponym) granite

An intrusive rock formed inside the Earth.